1. Field of the Invention
This invention relates to a structure of a car door. The car door is constituted by a panel body in which an outer panel and an inner panel are coupled, and a sash assembly supporting a windowpane at an upper part of the panel body.
2. Description of the Related Art
A car is usually provided with doors which enable passengers to comfortably get on and off.
Cars have a variety of shapes depending upon their applications, and are classified into a sedan having four doors and seats, a hatchback with a door at the back that opens upwards, and so on. The hatchback has a relatively straight contour, and has a uniform width at its front and back in order to improve the comfort of the passenger cabin and the ride. Usually, doors extend substantially straight along the length of the car. In one example of the related art, a windshield 110 attached to each front door and a glass slide 120 attached to each rear door are curved as shown in FIG. 7(b) of the accompanying drawings. The glass slide 120 has its rear end slightly curved by an angle θr toward the center of the car with respect to a base line Lx of the car. The windshield 110 is curved opposite to the glass slide 120 by an angle θ3 with respect to the base line Lx.
Referring to FIG. 11(a), a door 100 is constituted by a panel body P0 coupling an outer panel (not shown) and an inner panel 101, and a substantially rectangular sash 102. The rectangular sash 102 is independently roll-molded, is coupled to the panel body P0, and projects upward above a belt line Lb of the panel body P0. Referring to FIG. 11(b), a press-molded door 103 includes an outer panel (not shown) and an inner panel 104 which are coupled, a panel body P1 placed below a belt line Lb, and a sash S1 extending above the panel body P1 and the belt line Lb. The panel body P1 and the sash S1 are molded in succession.
Japanese Patent Laid-Open Publication Hei 6-106992 describes one example of the doors including independently molded sashes, and one example of press-molded doors.
It is assumed here that a hatchback has rear doors extending to its rear end, and gradually becomes narrow toward the rear end.
In the foregoing case, rear end pillars come close to the center of a body compared to center pillars. Further, upper parts of the rear doors immediately upstream of the rear end pillars are extensively curved compared with front parts of the rear doors.
When observed from above, each rear door has an upper edge which is constituted by a straight front, and a sloping rear. Accordingly, a door sash has a peripheral edge which is straight at its front and downwardly slopes at its rear.
The sash itself should be three-dimensionally curved in order to accomplish the foregoing shape.
However, it is very difficult to roll-mold the foregoing sash, and existing doors including independently molded sashes are usable only if some modifications are made. In the case of the press-molded door, the outer and inner panels are fabricated in a coupled state. An outer frame and an inner frame above the belt line are press-molded so as to have a straight front and a sloped part, and are coupled, which enables a sash to have a sloping part.
In order to be strong, the sash for the press-molded door has a hollow space, and a hem at an inner peripheral edge, and becomes relatively wide. Referring to FIG. 11(b), a thickness Ha of the roof-facing part of the sash is increased. Accordingly, the roof at an upper part of the door opening is widened. This means reduced degrees of design freedom.
The present invention has been contemplated in order to overcome problems of the related art, and is intended to provide a structure of a rear door which assures design freedom even when a car becomes gradually narrower toward end thereof.